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PubMed1997

[The diagnostic performance of echography and CT in pancreatic diseases producing extrahepatic cholestasis].

A hundred and fifty patients with jaundice and analytical suspicion of extrahepatic cholestasis were studied prospectively; history, laboratory investigation and ultrasound examination were realized. Computerized tomography was performed in 146 patients. Ultrasonography and computerized tomography findings were confirmed by CPRE o CPTH and surgery. Ultrasonography has a sensitivity of 92.6% while that of computerized tomography was 87.2% for the identification of dilated biliary ducts. The accuracy of ultrasonography was higher than the one obtained in computerized tomography in cholangiocarcinoma (sensitivity: 77.7%) and gallbladder carcinoma (sensitivity: 100%). Computerized tomography recognized choledocholithiasis (sensitivity: 83.3%) and ampullary carcinoma (sensitivity: 88.8%) with better accuracy. However for pancreatic carcinoma (sensitivity: 88.8%) and pancreatitis (sensitivity: 83.3%) both examinations had the same accuracy.

Adult↗

PubMed1999

Performance estimation of diagnostic tests for cervical precancer based on fluorescence spectroscopy: effects of tissue type, sample size, population, and signal-to-noise ratio.

Fluorescence spectroscopy may provide a cost-effective tool to improve precancer detection. We describe a method to estimate the diagnostic performance of classifiers based on optical spectra, and to explore the sensitivity of these estimations to factors affecting spectrometer cost. Fluorescence spectra were obtained at three excitation wavelengths in 92 patients with an abnormal Papanicolaou smear and 51 patients with no history of an abnormal smear. Bayesian classification rules were developed and evaluated at multiple misclassification costs. We explored the sensitivity of classifier performance to variations in tissue type, sample size, tested population, signal to noise ratio (SNR), and number of excitation and emission wavelengths. Sensitivity and specificity could be evaluated within +/- 7%. Minimal decrease in diagnostic performance is observed as SNR is reduced to 15, the number of excitation-emission wavelength combinations is reduced to 15 or the number of excitation wavelengths is reduced to one. Diagnostic performance is compromised when ultraviolet excitation is not included. Significant spectrometer cost reduction is possible without compromising diagnostic ability. Decision-analytic methods can be used to rate designs based on incremental cost-effectiveness.

Algorithms↗

PubMed2003

The diagnostic odds ratio: a single indicator of test performance.

Diagnostic testing can be used to discriminate subjects with a target disorder from subjects without it. Several indicators of diagnostic performance have been proposed, such as sensitivity and specificity. Using paired indicators can be a disadvantage in comparing the performance of competing tests, especially if one test does not outperform the other on both indicators. Here we propose the use of the odds ratio as a single indicator of diagnostic performance. The diagnostic odds ratio is closely linked to existing indicators, it facilitates formal meta-analysis of studies on diagnostic test performance, and it is derived from logistic models, which allow for the inclusion of additional variables to correct for heterogeneity. A disadvantage is the impossibility of weighing the true positive and false positive rate separately. In this article the application of the diagnostic odds ratio in test evaluation is illustrated.

Diagnosis↗

PubMed2000

Magnetic resonance imaging screening in women at genetic risk of breast cancer: imaging and analysis protocol for the UK multicentre study. UK MRI Breast Screening Study Advisory Group.

The imaging and analysis protocol of the UK multicentre study of magnetic resonance imaging (MRI) as a method of screening for breast cancer in women at genetic risk is described. The study will compare the sensitivity and specificity of contrast-enhanced MRI with two-view x-ray mammography. Approximately 500 women below the age of 50 at high genetic risk of breast cancer will be recruited per year for three years, with annual MRI and x-ray mammography continuing for up to 5 years. A symptomatic cohort will be measured in the first year to ensure consistent reporting between centres. The MRI examination comprises a high-sensitivity three-dimensional contrast-enhanced assessment, followed by a high-specificity contrast-enhanced study in equivocal cases. Multiparametric analysis will encompass morphological assessment, the kinetics of contrast agent uptake and determination of quantitative pharmacokinetic parameters. Retrospective analysis will identify the most specific indicators of malignancy. Sensitivity and specificity, together with diagnostic performance, diagnostic impact and therapeutic impact will be assessed with reference to pathology, follow-up and changes in diagnostic certainty and therapeutic decisions. Mammography, lesion localisation, pathology and cytology will be performed in accordance with the UK NHS Breast Screening Programme quality assurance standards. Similar standards of quality assurance will be applied for MR measurements and evaluation.

Adult↗

PubMed2000

Protocol for a national multi-centre study of magnetic resonance imaging screening in women at genetic risk of breast cancer.

The protocol of the national multicentre study of Magnetic Resonance Imaging (MRI) as a method of screening for breast cancer in women at genetic risk is described. The sensitivity and specificity of contrast-enhanced MRI will be compared with two-view X-ray mammography in a comparative trial. Approximately 500 women below the age of 50 at high genetic risk of breast cancer will be recruited per year for 3 years, with annual MRI and X-ray examination continuing for up to 5 years. A symptomatic cohort will be measured in the initial phase of the study to ensure consistent reporting between centres. The MRI examination will comprise an initial high-sensitivity screening measurement, followed by a high-specificity measurement in equivocal cases. Retrospective analysis will identify the most specific indicators of malignancy. Sensitivity and specificity, together with diagnostic performance, diagnostic impact and therapeutic impact will be assessed with reference to pathology, follow-up and changes in diagnostic certainty and therapeutic decisions. The psychological impact of screening in this high-risk group will be ascertained.

Journal Article↗

PubMed2000

Effects of age on the performance of common diagnostic tests for pulmonary embolism.

PURPOSE: The diagnosis of pulmonary embolism in the elderly is often difficult because of comorbid medical conditions, and perhaps also because diagnostic tests have a lower yield. We analyzed the diagnostic performance of common diagnostic tests for pulmonary embolism in different age groups. METHODS: We analyzed data from two large studies that enrolled 1,029 consecutive patients presenting to the emergency department with clinically suspected pulmonary embolism. The clinical probability of pulmonary embolism (high [>/=80%], intermediate, or low [</=20%]) was estimated by the treating physician. All patients underwent a sequential diagnostic protocol, including ventilation-perfusion lung scan, measurement of plasma D-dimer level, lower limb venous compression ultrasonography, and pulmonary angiography if the noninvasive work-up was inconclusive. RESULTS: The prevalence of pulmonary embolism increased progressively, from 12% in patients <40 years of age to 44% in those >/=80 years of age. The positive predictive value of a high clinical probability of pulmonary embolism was greater in the elderly (71% to 78% in those >/=60 years old versus 40% to 64% in those </=59 years old). The sensitivity of D-dimer testing was 100% in all age groups, but its specificity decreased markedly with age, from 67% in those </=40 years old to 10% in those >/=80 years old. The diagnostic yield of lower limb compression ultrasonography was greater in the elderly. The proportion of lung scans that were diagnostic (normal, near-normal, or high probability) decreased from 68% to 42% with increasing age. CONCLUSIONS: Age affects the performance of common diagnostic tests for pulmonary embolism and should be kept in mind when evaluating patients suspected of having this condition.

Adult↗

PubMed2005

Diagnostic mammography performance and race: outcomes in Black and White women.

BACKGROUND: A previous study compared the performance (sensitivity, specificity, positive predictive value, and cancer detection rate) of screening mammography in Black and White women. No study, to the authors' knowledge, has evaluated the difference in the performance of diagnostic mammography between Black and White women. METHODS: Univariate analysis was used to evaluate differences in characteristics and cancers between Black and White women. Stratified and adjusted logistic regression analyses were used to test the association of Black and White race with performance measures of diagnostic mammography. RESULTS: The sensitivity of diagnostic mammography was higher (91% vs. 84%) and specificity was lower (86% vs. 90%) among Black women compared with White women. After controlling for age, density, self-reported breast problems, and previous mammography, sensitivity was significantly higher (odds ratio [OR] = 1.82, 95% confidence interval [CI] = 1.22-2.80) and specificity was significantly lower (OR = 0.75, 95% CI = 0.70-0.81) among Black women. The crude cancer detection rate of mammography was higher for Black women (42.6/1000) than for White women (31.0/1000) and Black women had a higher proportion of cancers that were > 2.0 cm (57.4% vs. 46.2%) that were more often poorly differentiated (61.7% vs. 49.3%) and were more often estrogen-receptor and progesterone-receptor negative. CONCLUSIONS: Black women have lower specificity of diagnostic mammography and, consequently, more unnecessary workups than White women. Black women have higher sensitivity of diagnostic mammography, with cancers that are larger and more advanced than White women. Delay in responding to signs and symptoms would explain the size and later stage. However, more research is needed to understand the biologic differences of breast cancer characteristics between Black and White women.

Adult↗

PubMed2003

Mutual information as an index of diagnostic test performance.

OBJECTIVES: This paper demonstrates that diagnostic test performance can be quantified as the average amount of information the test result (R) provides about the disease state (D). METHODS: A fundamental concept of information theory, mutual information, is directly applicable to this problem. This statistic quantifies the amount of information that one random variable contains about another random variable. Prior to performing a diagnostic test, R and D are random variables. Hence, their mutual information, I(D;R), is the amount of information that R provides about D. RESULTS: I(D;R) is a function of both 1). the pretest probabilities of the disease state and 2). the set of conditional probabilities relating each possible test result to each possible disease state. The area under the receiver operating characteristic curve (AUC) is a popular measure of diagnostic test performance which, in contrast to I(D;R), is independent of the pretest probabilities; it is a function of only the set of conditional probabilities. The AUC is not a measure of diagnostic information. CONCLUSIONS: Because I(D;R) is dependent upon pretest probabilities, knowledge of the setting in which a diagnostic test is employed is a necessary condition for quantifying the amount of information it provides. Advantages of I(D;R) over the AUC are that it can be calculated without invoking an arbitrary curve fitting routine, it is applicable to situations in which multiple diagnoses are under consideration, and it quantifies test performance in meaningful units (bits of information).

Area Under Curve↗

PubMed2006

Correlation of radiologist rank as a measure of skill in screening and diagnostic interpretation of mammograms.

PURPOSE: To determine whether skill in the interpretation of screening mammograms is correlated with skill in the interpretation of diagnostic mammograms. MATERIALS AND METHODS: The institutional review board of the University of South Florida approved this study. This study was determined to be exempt from informed consent requirements because of the retrospective use of images and was conducted before HIPPA requirements were implemented. A total of 59 radiologists interpreted screening and diagnostic performance test sets of mammograms with a 1-year interval. Interpretations were recorded with modifications of the Breast Imaging and Reporting Data System. Radiologist skill was measured as the radiologist's ranking among his or her cohort in each of several measures of performance (ie, performance test receiver operating characteristic curve area, performance test screening sensitivity, performance test diagnostic sensitivity, and associated specificities). Correlations between radiologist rank in screening and rank in the diagnostic performance test measures were analyzed with the Spearman rank correlation statistical test. RESULTS: Radiologist rank in screening interpretations and in diagnostic interpretations was found to be significantly correlated in all measurements (P < .05). However, only two measurments (ie, receiver operating characteristic curve area rank correlation of 0.327 and sensitivity rank correlation of 0.402) remained significant after adjusting for multiple testing. The correlation between ranked screening specificity and ranked diagnostic specificity (0.296) was significant at only the .05 level. CONCLUSION: The interpretive performance of radiologists among their peers is moderately correlated between screening and diagnostic interpretations. Thus, proficiency in one area does not guarantee proficiency in the other area for some radiologists.

Clinical Competence↗

PubMed1997

Comparing the sensitivities and specificities of two diagnostic procedures performed on the same group of patients.

Studies of diagnostic accuracy are the most commonly performed diagnostic tests. These are carried out by using Decision Matrix tables in which sensitivities, specificities, predictive values and other ratios are calculated and compared. Various recoverable pitfalls and limitations of this method have been reported. This study reports additional further limitations of using this method as a statistical analytical tool. Decision protocol and formulae are presented to show how the sensitivities and specificities of tests are compared in order to make a decision. The study also shows how special tables can be constructed for the four results of comparative diagnostic tests (true positive, true negative, false positive and false negative), and cautions against the use of some 2 x 2 contingency tables. The procedures of how to use these special tables and formulae for comparing sensitivity and specificity and deriving confidence intervals for their difference are presented. It is also shown how it is possible to make a single inference from diagnostic test performance which will permit the determination of which test is better.

Diagnostic Imaging↗

PubMed2004

SCAI statement on ad hoc versus the separate performance of diagnostic cardiac catheterization and coronary intervention.

Coronary intervention may be combined with diagnostic cardiac catheterization or performed separately. In the early years of angioplasty, performing these procedures separately was standard practice. Gradually, ad hoc intervention (performing diagnostic angiography and coronary intervention within the same session) has become more common, largely because of its convenience for patients and efficiency for physicians. However, the safety and potential cost savings of this approach remain uncertain. Criteria for the appropriate use of ad hoc intervention have not been established. Ad hoc intervention is reasonable for many, but not appropriate for all patients and should not be considered standard therapy. This document updates an earlier review of this topic and provides suggestions for the use of ad hoc intervention as a routine strategy.

Angioplasty, Balloon, Coronary↗

PubMed1995

[The effect of performance of diagnostic and therapeutic procedures on successful treatment of hemopneumothorax in isolated thoracic trauma].

Influence of performed diagnostic and therapeutic procedures on the outcome of the treatment of traumatic hemopneumothorax during isolated chest trauma. The aim of this study is the assessment of the influence of performed diagnostic and therapeutic procedures on the outcome of hemopneumothorax as a part of isolated chest trauma. The main group consists of 51 patients with hemopneumothorax. Patients with pneumothorax without effusion represent the first control group; the second control group consist of patients treated because of iatrogenic pneumothorax. In the main and control groups the analysis of clinical, roentgenographic and functional parameters was made, together with the analysis of particular therapeutic procedures, the estimation of the success of the treatment was based on roentgenographic and functional parameters. The higher incidence of hemopneumothorax compared with control groups during chest trauma in the analyzed material is statistically significant. The occurrence of bilateral hemopneumothorax in 10% of cases emphasizes the need of adequate roentgenographic assessment of injured patients. Regardless of the intensity of the trauma, symptoms do not always indicate the existence of hemopneumothorax. The number of fractured ribs is not of significant importance in terms of the occurrence of hemopneumothorax or pneumothorax. Severe dyspnea can be accompanied even with a smaller collapse of the lung independently of the amount of blood in the pleural cavity. Oxygenation in the arterial blood is impaired with the great and small pulmonary collapse. Hemodynamic disorders existed in 14% all cases. The higher frequency of operative treatment in the main group is statistically significant. The majority of cases of traumatic hemopneumothorax can be successfully treated by the conservative treatment. Accompanying complications do not have greater influence on the outcome.

Adult↗

PubMed2006

Determination of interobserver variability for identifying inducible left ventricular wall motion abnormalities during dobutamine stress magnetic resonance imaging.

AIMS: To determine the interobserver variability for identifying inducible left ventricular (LV) wall motion abnormalities during high-dose dobutamine/atropine stress cardiovascular magnetic resonance (DSMR). METHODS AND RESULTS: Four readers from various institutions were supplied with the image data from 150 consecutive DSMR examinations and asked to grade wall motion and image quality throughout graded doses of dobutamine infusion administered to achieve 85% of the maximum age-predicted heart rate. Inducible ischaemia was identified if more than one segment demonstrated a new or worsening LV wall motion abnormality, and significant stenosis was defined as > or =50% luminal diameter reduction by quantitative contrast coronary angiography. Seventy-seven patients (51%) had luminal narrowings > or =50%. Diagnostic performance (sensitivity, specificity, diagnostic accuracy) of all readers was 78.2, 87.0 and 82.5%. Disagreement between two readers occurred in every seventh examination. Agreement on the presence or absence of inducible wall motion abnormalities was moderate (mean kappa value 0.59, range 0.52-0.76). Diagnostic performance and disagreement were independent of the presence of luminal narrowings > or =50% or the number of diseased coronary vessels. Image quality was regarded excellent in 89.3% of standard views. CONCLUSION: In the setting of multiple observers from different institutions performing a diagnostic reading of DSMR examinations carried out at a single centre, the interobserver variability was low for identifying inducible LV wall motion abnormalities indicative of coronary arterial luminal narrowings > or =50%.

Cardiotonic Agents↗

PubMed1999

Reliability of the routine cytological diagnosis in bladder cancer.

OBJECTIVES: To establish the reliability of three cytopathologists for cytological diagnosis of primary bladder tumors. METHODS: Preoperative voided urine specimens of 71 patients with bladder cancer and 55 noncancer controls were retrospectively and blindly reviewed by 3 independent cytologists, and their results compared. The estimation of the interobserver agreement was calculated using the weighted kappa coefficient. A multivariate analysis was carried out to identify the factors associated with the disagreement between the three observers. The sensitivity and specificity for each of the participants was calculated in order to clearly identify the origin of the disagreement, in terms of the performance of the diagnostic test in the hands of each observer. A comparison of the overall diagnostic performance was made by plotting sensitivity versus 1-specificity. RESULTS: The weighted kappa coefficient among the 3 observers was 0.46. The multivariate analysis did not identify any variable that could have caused such disagreement. Vast differences in sensitivity and specificity were detected between observer 1 (sens. 0.90, spec. 0.45) and observers 2 (sens. 0.67, spec. 0.72) and 3 (sens. 0.71, spec. 0.80), but the overall diagnostic performance (sensitivity vs. 1-specificity) was superimposable in the 3 cases (p = NS). CONCLUSIONS: Simple, reproducible and agreed-on-diagnostic criteria should be established to yield reliable results in a group of cytologists. The consideration of individual diagnostic performances can give a false idea of homogeneity between observers. In this field, concordance analysis makes quality control reliable and should be a routine procedure of any pathology department.

Carcinoma, Transitional Cell↗

PubMed1999

[Reliability of routine cytological diagnosis in bladder cancer].

OBJECTIVES: To establish the reliability of three cystopathologists for cytological diagnosis of primary bladder tumors. METHODS: Pre-operative voided urine specimens of 71 patients with bladder cancer and 55 healthy controls were retrospectively and blindly reviewed by 3 independent cytologists, and their results--positive for bladder cancer, negative or inconclusive--were compared with each other. The estimation of the interobserver agreement was calculated using the weighted kappa-coefficient (k). A multivariative analysis was carried out to identify the factors associated with the disagreement among the three observers. The sensitivity and specificity for each of the participants were calculated in order to clearly identify the origin of the disagreement, in terms of the performance of the diagnostic test in the hands of each observer. A comparison of the overall diagnostic performance was made by plotting sensitivity versus 1-specificity. RESULTS: The weighted k coefficient among observers was 0.46. The multivariative analysis did not identify any variable that could have caused such disagreement. Large differences in sensitivity and specificity were detected between observer number 1 (sens., 0.90, spec., 0.45) and observers number 2 (sens., 0.67, spec., 0.72) and number 3 (sens., 0.71, spec., 0.80), but the overall diagnostic performance (sensitivity vs 1-specificity) was superimposable in the three cases (p = ns). CONCLUSIONS: Simple, reproducible and agreed-on diagnostic criteria should be established to yield reliable results in a group of cytologists. The consideration of individual diagnostic performances can give a false idea of homogeneity between observers. In this field, concordance analysis makes quality control reliable and should be a routine procedure of any pathology department.

Female↗

PubMed2001

Accuracy of imaging technologies in the diagnosis of acute cardiac ischemia in the emergency department: a meta-analysis.

STUDY OBJECTIVE: We sought to quantitatively evaluate the evidence on the diagnostic performance of imaging technologies (including rest and stress echocardiography and technetium-99m sestamibi scanning) for the diagnosis of acute cardiac ischemia and acute myocardial infarction in the emergency department. METHODS: We conducted a systematic review and meta-analysis of the English-language literature published between 1966 and December 1998. Both prospective and retrospective studies qualified for the assessment of diagnostic performance. Diagnostic performance was assessed by means of random-effect estimates of test sensitivity, specificity, and the diagnostic odds ratio and was summarized by using summary receiver-operating characteristic curves. RESULTS: Diagnostic accuracy was evaluated in 10 studies of rest echocardiography, 2 studies of dobutamine stress echocardiography, and 6 studies of technetium-99m sestamibi scanning. However, only 3 rest echocardiography and 5 technetium-99m sestamibi studies evaluated patients strictly in the ED setting. Patient populations were often highly selected to represent low- or moderate-risk groups. When limited to ED studies, rest echocardiography showed excellent sensitivity of 93% (95% CI, 81% to 97%) and good specificity of 66% (95% CI, 43% to 83%). The results were similar when all studies were considered, including data from reports of admitted patients and patients sent to the cardiac care unit. There was insufficient literature on stress echocardiography in the ED to properly assess the technology. Technetium-99m sestamibi scanning also showed excellent sensitivity (range, 91.5% to 100%) and good specificity (range, 49.3% to 84.4%) for acute myocardial infarction; for acute cardiac ischemia, the random-effects pooled sensitivity was 89% (95% CI, 73% to 96%), and the pooled specificity was 77% (95% CI, 63% to 87%). CONCLUSION: For selected low- and moderate-risk patient groups, echocardiography and technetium-99m sestamibi imaging appear to have very good diagnostic performance with a similar sensitivity and specificity profile. More evidence should be accumulated on their performance specifically in the ED setting.

Acute Disease↗

PubMed2026

Transcriptome-wide association analysis of Alzheimer's disease: construction and clinical validation of transcriptomic risk scores.

Early identification of individuals at high risk for Alzheimer's disease (AD) is crucial for disease prevention and intervention. This study aims to develop AD-specific transcriptomic risk scores (TRSs) through multi-tissue transcriptome-wide association study (TWAS) and to evaluate its clinical utility in AD diagnosis and risk prediction. Using GWAS summary statistics combined with expression quantitative trait loci (eQTL) data from 14 tissues, a multi-tissue TWAS approach was applied to identify AD-associated genes. Peripheral blood RNA expression data from the ADNI and GEO databases were used to construct the AD-specific TRSs. The associations of TRSs with AD pathological features and cognitive function were assessed in two independent cohorts. Furthermore, the diagnostic performance, differential diagnostic capability, and risk prediction efficiency of TRSs were evaluated. The TWAS identified 131 genes significantly associated with AD. The TRSs were significantly elevated in patients with AD and mild cognitive impairment (MCI) compared to cognitively normal (CN) individuals, and showed significant correlations with AD pathological markers and cognitive performance. When combined with APOE4 status, the TRSs demonstrated robust diagnostic ability for AD and MCI. When combined with age, the TRSs showed good diagnostic performance in distinguishing AD from frontotemporal dementia (FTD) (AUC = 0.86). Additionally, the TRSs effectively predicted the risk of progression to AD in non-AD individuals (HR = 1.74). The AD-specific TRSs developed in this study shows promising clinical utility in AD diagnosis, differential diagnosis, and risk prediction, providing valuable translational medical evidence for early screening and precision prevention of Alzheimer's disease.

Humans↗

PubMed1993

Digital subtraction temporomandibular joint tomography.

Receiver operating characteristics analysis was performed to demonstrate differences in diagnostic performance among conventional tomograms, digitized tomograms, and subtraction tomograms. Digital subtraction tomography was found to be the best imaging modality for detecting artificially created lesions in the two selected temporomandibular joint locations. There was a statistically significant difference in diagnostic performance between conventional tomograms and subtraction tomograms for the detection of temporomandibular joint bony lesions. There was also a statistically significant difference in diagnostic performance between digitized tomograms and subtraction tomograms in the detection of these bony lesions. There was no statistically significant difference in diagnostic performance between conventional tomograms and digitized tomograms for the detection of temporomandibular joint bony lesions. The significance level was set at p = 0.05. Results of the analyses of variance showed that with digital subtraction tomograms, observer reliabilities were higher than with conventional and digitized tomograms.

Evaluation Studies as Topic↗